Abstract: Non-bacterial thrombotic vegetations occurring on the heart valves were usually called non-bacterial thrombotic endocarditis（NBTE）.This paper reports the study of 12 cases of such lesion.The.primary diseases were malignant tumors in 7.chronic rheumatic valvular disease in 4,and congenital heart disease in 1.It is interesting to note that all the 7 cases of malignant tumors were adenocarcinomas,and 5 cases of heart disease were all in the stage of cardiac failure.In the majority of cases the vegetations were situated on the valves of the left heart,only in I case it was on the tricuspid valve.The vegetations composed of fibrin,a few platelets and red blood cells.They ranged from 1—2 mm to 1.5 cm or more in diameter,and from 1 to more than 10 in number.They were fragile and easily broken as emboli.The main clinical manifestations and the most severe outcome of this lesion was embolisms,particularly in the brain and heart.In 9 cases infarcts were found in one or several organs,being commonest in the brain.It is suggested that if a patient,known to be suffering from adenocarcincma or chronic valvular disease with heart failure,should show symptoms and signs of cerebral infarction,NBTE must be taken into consideration,and when a cerebral embolism is evident but the source of embolus is not yet determined,NBTE must also be borne in mind.In 9 cases a few micro-thrombi were found in small blood vessels of one or several organs.This finding, together with thrombopenia present in 6 of the cases during life,suggests that there was DIG before death.Our study gives support to the idea that NBTE is merely a manifestation of DIC,which runs a subacute or chronic course.The association of adenocarcinoma with the occurrence of NBTE is a problem calling for further study.It could be that the products of these malignant tumors enter the blood,acting as a hypercoagulation factor,and thus inducing DIG. It is important to have a full understanding of the pathogenesis of this lesion in order to prevent its formation.